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package org.apache.juneau.rest;

import org.apache.juneau.rest.annotation.*;

/**
 * Class used to resolve {@link Class} objects to instances.
 * 
 * <p>
 * Used to convert classes defined via {@link RestResource#children() @RestResource.children()} into child instances.
 * 
 * <p>
 * Subclasses can be created to provide customized resource resolution.
 * These can be associated with REST resources in one of the following ways:
 * <ul>
 * 	<li>{@link RestResource#resourceResolver() @RestResource.resourceResolver()} annotation.
 * 	<li>{@link RestContextBuilder#resourceResolver(Class)}/{@link RestContextBuilder#resourceResolver(RestResourceResolver)}
 * 		methods.
 * </ul>
 * 
 * Implementations must provide one of the following public constructors:
 * <ul>
 * 	<li>RestResourceResolver()
 * 	<li>RestResourceResolver(RestContext)
 * </ul>
 * 
 * <h5 class='section'>See Also:</h5>
 * <ul>
 * 	<li class='link'><a class="doclink" href="../../../../overview-summary.html#juneau-rest-server.ResourceResolvers">Overview &gt; juneau-rest-server &gt; Resource Resolvers</a>
 * </ul>
 */
public interface RestResourceResolver {

	/**
	 * Represents no RestResourceResolver.
	 * 
	 * <p>
	 * Used on annotation to indicate that the value should be inherited from the parent class, and
	 * ultimately {@link BasicRestResourceResolver} if not specified at any level.
	 */
	public interface Null extends RestResourceResolver {}
	
	/**
	 * Resolves the specified class to a resource object.
	 * 
	 * <p>
	 * Subclasses can override this method to provide their own custom resolution.
	 * 
	 * <p>
	 * The default implementation simply creates a new class instance using {@link Class#newInstance()}.
	 * 
	 * @param parent 
	 * 	The parent resource (i.e. the instance whose class has the {@link RestResource#children() @RestResource.children()} annotation.
	 * @param c The class to resolve.
	 * @param builder The initialization configuration for the resource.
	 * @return The instance of that class.
	 * @throws Exception If class could not be resolved.
	 */
	Object resolve(Object parent, Class<?> c, RestContextBuilder builder) throws Exception;
}
